feat(KeySignatures): add EngravingRules.RenderKeySignatures (#894) (false now supported)

closes #894

src/MusicalScore/Graphical/EngravingRules.ts

@@ -255,6 +255,7 @@ export class EngravingRules {
     public RenderLyrics: boolean;
     public RenderMultipleRestMeasures: boolean;
     public AutoGenerateMutipleRestMeasuresFromRestMeasures: boolean;
+    public RenderKeySignatures: boolean;
     public RenderTimeSignatures: boolean;
     public DynamicExpressionMaxDistance: number;
     public DynamicExpressionSpacer: number;
@@ -548,6 +549,7 @@ export class EngravingRules {
         this.RenderLyrics = true;
         this.RenderMultipleRestMeasures = true;
         this.AutoGenerateMutipleRestMeasuresFromRestMeasures = true;
+        this.RenderKeySignatures = true;
         this.RenderTimeSignatures = true;
         this.ArticulationPlacementFromXML = true;
         this.FingeringPosition = PlacementEnum.Left; // easier to get bounding box, and safer for vertical layout

src/MusicalScore/Graphical/VexFlow/VexFlowMeasure.ts

@@ -242,6 +242,9 @@ export class VexFlowMeasure extends GraphicalMeasure {
      * @param currentClef the valid clef. Needed to put the accidentals on the right y-positions.
      */
     public addKeyAtBegin(currentKey: KeyInstruction, previousKey: KeyInstruction, currentClef: ClefInstruction): void {
+        if (!this.rules.RenderKeySignatures) {
+            return;
+        }
         this.stave.setKeySignature(
             VexFlowConverter.keySignature(currentKey),
             VexFlowConverter.keySignature(previousKey),